Flame and heat resistant yarns and fabrics

ABSTRACT

The present invention relates to flame and heat resistant yarns comprising polyacrylate fibers, and to flame retardant textile materials formed from such yarns. The flame and heat resistant yarns include a series of polyacrylate fibers blended with a series of companion fibers, which can include other flame resistant fibers. The polyacrylate fibers provide enhanced char strength to the yarns, while the companion fibers can be selected to provide increased tensile strength and other desired properties to the flame and heat resistant yarns. The flame and heat resistant yarns can be used to form fabrics or textile materials for use in a variety of applications, which fabrics exhibit a reduced fabric char length when subject to vertical flammability testing, and meet flammability requirements for any or all of National Fire Protection Association Standards NFPA 1971, NFPA 1975, NFPA 2112, NFPA 1951, NFPA 1977, and/or NFPA 70E; or which further meet or exceed the flame resistance requirements achieving an SFI Foundation performance rating of 3.2A/1 to SFI 3.2A/40, and/or Code of Federal Regulations 16 CFR 1633.

FIELD OF THE INVENTION

The present invention generally relates to yarns having flame retardant and heat resistant properties and the resultant fabrics formed therefrom. In particular, the present invention relates to the formation of flame retardant and heat resistant yarns incorporating polyacrylate fibers, and the formation of fabrics utilizing such yarns, which meet or exceed the vertical flammability and thermal stability requirements of one or more fabric materials specified in National Fire Protection Association Standards NFPA 1971, NFPA 1975, NFPA 2112, NFPA 1951, NFPA 1977, and/or NFPA 70E, or which further meet or exceed the flame resistance requirements achieving an SFI Foundation performance rating of 3.2A/1 to SFI 3.2A/40, and/or Code of Federal Regulations 16 CFR 1633.

BACKGROUND OF THE INVENTION

Protective garments formed from fire retardant and/or heat resistant fabrics have long been in use for protecting workers in a variety of occupations. For example, firefighters, military and emergency personnel, and workers in fields such as auto racing, chemical/petroleum drilling and refining, steel making and other occupations where workers are at a high risk of exposure to fire, flame, and/or excessively high temperatures, generally are required to wear fire or flame resistant protective garments. For a garment to offer sufficient protection to meet flame and thermal requirements, the fabric from which the garment is constructed must not sustain a flame, melt, and/or stick to the skin of the wearer when exposed to fire or high temperatures, and must have minimal thermal shrinkage and thermal conductivity. At the same time, during flame exposure, the garment must offer substantial resistance to fabric rupture or tearing that could lead to direct flame impingement to the skin of the wearer. The National Fire Protection Association (NFPA) has promulgated a number of industry standards that govern protective clothing performance, including:

-   -   NFPA 1971: Standard on Protective Ensembles for Structural Fire         Fighting and Proximity Fire Fighting (2007);     -   NFPA 1975: Standard on Station/Work Uniforms for Fire and         Emergency Services (2004);     -   NFPA 2112: Standard on Flame-Resistant Garments for Protection         of Industrial Personnel Against Flash Fire (2007);     -   NFPA 1951: Standard on Protective Ensembles for Technical Rescue         Incidences (2013);     -   NFPA 1977: Standard on Protective Clothing and Equipment for         Wildland Firefighting (2011).     -   NFPA 70E: Standard for Electrical Safety in Workplace (2012);         To be judged compliant, flame resistant textile materials         require testing by various NFPA and American Society for Testing         and Materials (ASTM) test methods, including:     -   ASTM D6413: Standard Test Method for Flame Resistance of         Textiles (Vertical Method);     -   ASTM F1559: Standard Performance Specification for Determining         the Arc Rating of Materials for Clothing;     -   ASTM F1060: Standard Test Method for the Thermal Protective         Performance of Materials for Protective Clothing for Hot Surface         Contact;     -   NFPA 1971 Section 8.2 Thermal Protective Performance (TPP) Test;     -   NFPA 1971 Section 8.4 Heat and Thermal Shrinkage Test.     -   ISO 17992 Clothing for protection against heat and         flame—Determination of heat transmission on exposure to both         flame and radiant heat.         The various ASTM testing standards measure a material's         performance against selected NFPA requirements which vary by the         intended end use of the fabric materials being tested.

For example, ASTM Standard D6413 provides the standard practice and test protocol for vertical flammability resistance of fabrics. In this test, a fabric specimen is held in a vertical orientation, with its lower edge being exposed to a flame. In order to meet the requirements of the NFPA 1975 standard, the fabric specimen tested must exhibit a char length of less than or equal to six inches after exposure to a flame for twelve seconds, while under the NFPA 2112 standard, the fabric must exhibit a char length of less than or equal to four inches after a twelve second flame exposure.

As noted above, it is important that a protective garment provide thermal insulation to the user and not rupture during flame contact. These properties are measured using the Thermal Protective Performance (TPP) test ISO 17492 set forth in Section 8.10 of NFPA 1971 Standard. The test exposes a horizontal fabric or layers of fabrics to a combined radiant/convective thermal flux of 2.0 cal/cm²·sec. The heat transfer through the system is measured using a backside copper calorimeter. As measured by the calorimeter, the timed rate of rise in temperature is compared to the time needed before the energy causes a second degree human skin burn. Fabrics which break open during testing quickly reach the energy necessary for burn injury. The test method assigns fabrics a “TPP Rating,” defined as the time in seconds to reach a second degree skin burn multiplied by the heat flux (typically 2.0 cal/cm²·sec). The SFI Foundation sets its ratings for heat and/or flame resistant protective garments based upon the TPP Rating of the fabric materials from which the garments are constructed. For example, an SFI suit with a 3.2A/40 rating has a measured TPP value of 40 which predicts 20 seconds of protection before a second degree burn injury is reached.

Flame resistance is also required for some non-apparel uses such as carpets, wall coverings, awnings, curtains, furniture and mattress fire blocking, and aircraft, trains, ships, buses, and automobiles. As one example, fabric fire barriers for mattresses and furniture must pass flame resistance tests promulgated in the Code of Federal Regulations (16 CFR 1633).

During mattress testing as specified in 16 CFR 1633, the top and sides of a full-sized mattress set, comprising a mattress and a foundation that each incorporate a fire-blocking fabric, is exposed to a specified flaming ignition source and allowed to burn freely. After exposure to flames of several intensities, the Peak Heat Release and Total Heat Release of the burnt mattress set are calculated. To comply with the standard, the Peak Heat Release measured during the test set shall not exceed 200 kilowatts at any time during the 30 minute duration of the test. Furthermore, the Total Heat Release shall not exceed 15 megajoules for the first 10 minutes of the test. Rupture of the fire-blocking fabric during flame exposure allows the flame to ignite the combustible internal materials of the mattress set, and as a result, a mattress set which exhibits rupturing of the fire blocking fabric thereof cannot meet the specified performance requirements. It is thus imperative that the fire-blocking fabric have high char strength to prevent fabric rupture and penetration of the flame into interior of the mattress set.

A number of flame retardant and/or heat resistant fabrics have been developed for forming protective garments that are designed to comply with the NFPA requirements for such fabrics. It further is common for conventional fire protective fabrics to incorporate para- and/or meta-aramid fibers, such as sold by DuPont Protective Systems under the trade names Kevlar® and Nomex®. These para- and meta-aramid fibers, and other, commonly used flame retardant fibers including polybenzimidazole, polybenzoxazole, polyimide, phenolic, melamine, modacrylic, oxidized polyacrylonitrile, and polysulfonamide fibers generally provide excellent resistance to flame and exposure to high temperatures.

Such fibers can, however, be expensive, which correspondingly makes garments formed therefrom likewise expensive to manufacture. In addition, while some fibers may exhibit high strength and resistance to tearing, they also tend to have limited flexibility and can exhibit increased rigidity and stiffness. As a result, the garments formed from some such fabrics, in addition to their expense, can be uncomfortable to wear, with limited flexibility that can significantly restrict the range of movement of the wearer. Other flame resistant fibers exhibit low strength which results in fabrics with poor resistance to tearing and abrasion and shorter garment life. Generally, para-aramid, meta-aramid and other conventionally used highly flame resistant, high strength fibers are difficult to dye such that fabrics formed therefrom typically will be limited to or influenced by the base color or polymer structure of such fibers.

Other types of flame resistant fibers also have been developed. For example, polyacrylate fibers are known to have a high resistance to burning when exposed to a flame. However, polyacrylate fibers generally have been found to exhibit limited tensile strength, such that fabrics made therefrom can rupture or tear more easily than para-aramid or meta-aramid fabrics. As a result, polyacrylate fibers typically have been limited to non-woven textiles wherein fiber strength has not been a substantial requirement of the finished textile product. Such polyacrylate fibers are, however, generally less costly than commonly used flame retardant fibers, such as para- or meta-aramids, polyimides, polybenzimidazole, polybenzoxazole, polysulfonamide and oxidized polyacrylonitrile fibers, and generally exhibit an enhanced ability for dyeing.

Accordingly, it can be seen that a need exists for improved flame and heat retardant or resistant yarns and fabrics made therefrom which exhibit char strength and thermal resistance sufficient to meet or exceed industry standards, but which are economical to produce and which exhibit enhanced flexibility, softness, wearability, dyeability and other desirable features, without substantially diminishing the strength and/or resistance to tearing of the resultant fabrics.

SUMMARY OF THE INVENTION

Briefly described, in one embodiment, the present invention is directed to a flame retardant and heat resistant yarn and fabrics formed therefrom. The flame retardant and heat resistant yarn generally will be formed as a staple spun yarn, and can be formed with or without a filament core, formed as a sheath or composite yarn comprising a series of flame retardant polyacrylate fibers spun together with a series of companion fibers. The companion fibers can include a variety of different material fibers and generally will be selected to provide desired properties to be combined with the char strength and flame resistance of the polyacrylate fibers. For example, the companion fibers can be selected from one or more various natural and/or synthetic fibers including lyocell, viscose rayon, cotton, wool, polyesters, polyamides, polyphenylene sulfide, polyetherimide, flame retardant viscose rayon, flame retardant lyocell, flame retardant wool, flame retardant cotton, flame retardant polyesters, flame retardant polyarnides, acrylic, modacrylic, polybenzoxazole, polybenzimidazole, oxidized polyacrylonitrile, melamine, phenolic, polyolefins, polysulfonamide, liquid crystal polymer, polyvinylchloride, polytetrafluoroethylene, metal, glass, ceramic, and/or other inorganic fibers, and combinations thereof, which are selected to provide increased tensile strength and resistance to tearing, a softer feel and texture, greater flexibility, and/or various other desired properties. The companion fibers further can be selected from natural and/or synthetic staple fibers that have a lower char strength than the polyacrylate fibers with which they are combined, but which are similarly less expensive than commonly used flame retardant and heat resistant fibers.

The ratio of polyacrylate to companion fibers will be balanced so as to provide the resultant fabric formed by the flame retardant and heat resistant yarns with a desired char strength, as provided by the polyacrylate fibers that meets or exceeds intended NFPA or other Standards, while at the same time providing a necessary level of tensile strength. Other properties, such as an enhanced softness and feel, enhanced flexibility and various other desired properties such as dyed colors also can be engineered into the flame and heat resistant yarn and fabric. The flame and heat resistant yarns further can be woven, knitted, or otherwise formed into a knit, woven or non-woven fabric or other textile material, and further can be used for the production of various flame and heat resistant fabrics for a variety of applications, including fabrics formed from the flame and heat resistant yarns substantially alone or in combination with additional yarns having other, varying compositions. Such fabrics further can be produced with a lower cost than many conventional flame or fire and heat resistant fabric materials while still providing a tensile strength and char length that meet or exceed applicable NFPA Standards.

Various objects, features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective illustration of one example embodiment of a flame and heat resistant yarn formed according to the principles of the present invention.

FIG. 1B is a cross sectional view illustrating the spun yarn of FIG. 1A.

FIG. 2 is an illustration of the test arrangement for vertical flammability testing of a fabric according to ASTM Standard 6413.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in greater detail in which like numerals indicate like parts throughout the several views, the present invention generally relates to flame and heat resistant yarns and to fabric or textile materials formed therefrom. Such fabric materials can include woven, knit and/or non-woven materials such as for use in forming fire/flame protective garments and various other flame resistant articles such as carpets, wall coverings, upholstery materials, automotive interiors, window treatments, bedding materials, and/or various other uses.

As generally illustrated in FIGS. 1A and 1B, the flame and heat resistant yarns formed according to the principles of the present invention are formed as staple spun yarns 10. In particular, the present invention is directed to the economical formation of high performance flame and heat resistant yarns which exhibit heat and flame resistant properties, including required char strength and fabric char length when the yarns and fabrics formed therefrom are exposed to flame and/or high levels of heat, which are designed to meet or exceed NFPA and/or 16 CFR 1633 protective fabric standards, but which are able to be manufactured more economically and which exhibit further properties such as necessary tensile strength and resistance to tearing, increased flexibility, softness and/or feel, enhanced dyeability and other desired finished properties.

As also generally illustrated in FIGS. 1A and 1B, the flame and heat resistant yarns 10 generally can be formed without requiring a supporting filament or core. The yarns further are produced using a spinning process, such as a ring, air jet, open end or “DREF” type spinning frame and spinning process. The finished yarns can be further spun, twisted or wrapped with additional yarns to form composite engineered yarns. The finished yarns also generally are able to endure physical and mechanical abuses of knitting or weaving machines, or other processes for forming the yarns into woven, knit and/or non-woven fabrics having necessary properties such as increased heat resistance and char length, and desired levels of tensile strength, flexibility, softness, etc., and which can be produced at a more economical cost. Still further, the flame and heat resistant yarns and fabrics formed therefrom can be subjected to dyeing in a variety of colors and hues thereof, without the chemical dyes adversely affecting the flame and heat resistant properties provided by the polyacrylate fibers.

As illustrated in FIGS. 1A and 1B, the flame and heat resistant yarn 10 will be formed with a body or sheath 11 incorporating a series of spun fibers, strands and/or other thread-like structures, including a series of polyacrylate fibers (indicated by phantom lines 12) and companion fibers 15. The polyacrylate fibers 12 and companion fibers 15 generally will be spun together to form a flame and heat resistant spun yarn 10, with the resultant yarn generally including a higher percentage of companion fibers as compared to the polyacrylate fibers.

The polyacrylate fibers 12 can include acrylic fibers which are cross-linked, such as by using a process such as disclosed in WO 2008/128660, the disclosure of which is incorporated by reference as if fully set forth herein, or other, similarly formed fibers, and generally will have a high resistance to burning as measured by the limiting oxygen index, or LOI, preferably in a range of approximately 35-45%. The polyacrylate fibers selected further preferably will not melt or drip, and will not continue to burn after a flame is removed, as exhibited during burn testing, and further will yield a carbonaceous char that remains flexible after burning. Examples of polyacrylate fibers that can be utilized include Inidex™, PyroTex®, and Didon® cross-linked polyacrylate fibers.

As noted, the polyacrylate fibers 12 will be spun together with a series of companion fibers 15, which can include natural and synthetic fibers selected to provide a desired increase in tensile strength and other physical properties to the resultant yarn 10 and fabrics formed therefrom, and which are compatible with the flame and heat resistant properties of the polyacrylate fibers. For example, the companion fibers can be selected from various natural and/or synthetic fibers including, but not limited to, lyocell, viscose rayon, cotton, wool, polyesters, polyarnides, polyphenylene sulfide, polyetherimide, flame retardant lyocell, flame retardant viscose rayon, flame retardant wool, flame retardant cotton, flame retardant polyesters, flame retardant polyarnides, acrylic, modacrylic, para- and/or meta-aramids, polybenzoxazole (PBO), polybenzimidazole (PBI), polyimide, oxidized polyacrylonitrile, melamine, phenolic, polyolefins, polysulfonamide, liquid crystal polymer, polyvinylchloride, polytetrafluoroethylene, metal, glass, ceramic and/or other inorganic fibers.

Preferably, the companion fibers selected will include fibers that incorporate other desired properties such as, but not limited to strength, flexibility, softness, durability and/or other desired properties, and which also generally will be of a substantially lower cost than conventionally used fibers such as para- and meta-aramid fibers, polybenzimidazole, and/or polybenzoxazole fibers. Such lower cost fibers will be blended with the polyacrylate fibers in various compositions, which can include a selected type of companion fiber alone, or can include more than 1 different companion fiber to form a multi-component yarn having various desired, selected properties in addition to improved char strength.

Lower cost companion fibers, including companion fibers with poorer flame resistance or lower char strength but a higher tensile strength and flexibility than the polyacrylate fibers, may be combined in a balanced ratio with the polyacrylate fibers. This ratio of companion fibers to polyacrylate fibers is balanced based upon the finished yarn incorporating a desired level of char strength and thermal shrinkage (from the polyacrylate fibers) versus a necessary fabric tensile and tear strength. Typically, fabrics formed from the present yarns can comprise about 5 to 95% polyacrylate fibers in order to provide a flame resistant, durable yarn for the formation of fabrics that meet or exceed existing various NFPA 16 CFR 1633 Standards for flame retardant fabrics formed from such composite yarns, but which yarns are also significantly more cost effective to manufacture, more readily dyeable and have an enhanced flexibility as compared to more conventional fabrics formed principally of para- and meta-aramid fibers, polybenzimidazole, polybenzoxazole, polyimides, modacrylic, and/or oxidized polyacrylonitrile fibers. As a further result of the reduction in the fiber costs incurred in forming the present flame and heat resistant yarns, the corresponding costs of flame and heat resistant fabrics formed therefrom could be reduced as much as 50% over other char forming fibers such as para- or meta-aramids. Savings could be even higher, up to as much as about 1000% over yarns formed solely from conventional PBI or PBO flame and thermal resistant fibers.

In one embodiment, the spun composite yarns 10 can incorporate approximately 5% to 95% by weight of the polyacrylate fibers, with the remaining approximately 5% to 95% by weight of the composite yarns comprising the companion fibers. In a further embodiment, the polyacrylate fibers can comprise approximately 35% to 80% by weight of the polyacrylate fibers, although greater or lesser amounts also can be used, for example, about 2% to about 50% in other potential embodiments. The percentage of the polyacrylate fibers further can be varied depending upon variation of char strength/length desired for the finished yarns/fabrics formed therefrom, and the necessary or desired tensile strength of the finished yarns and any fabrics formed therefrom.

For example, for forming protective flame and heat resistant garments, the companion fibers can be selected to include high strength fibers that have at least a desired flame resistance or char strength, but which further have an increased tensile strength and resistance to tearing when the fabrics are exposed to flames and/or high temperatures. Alternatively, flame barrier fabrics designed for mattress or furniture can have lower fabric strength, but will be provided with a sufficient char strength and flame resistance sufficient to maintain the barrier between the flame source and inside materials of mattresses or upholstered furniture in accordance with applicable state, federal and/or industry regulations and standards.

The flame and heat resistant yarns 10 of the present invention also can be provided with additional strengthening or supporting fibers or filaments that can be blended with the companion fibers 15 and spun with the polyacrylate fibers in order to form the composite heat resistant yarns. For example, additional amounts of strengthening fibers in a range of about 5% to 95% can be used, although other, varying amounts also can be used. Such fibers can be selected from various natural and/or synthetic fibers including, but not limited to, lyocell, viscose rayon, cotton, wool, polyesters, polyarnides, polyphenylene sulfide, polyetherimide, flame retardant lyocell, flame retardant viscose rayon, flame retardant wool, flame retardant cotton, flame retardant polyesters, flame retardant polyarnides, acrylic, modacrylic, para- and/or meta-aramids, polybenzoxazole, polybenzimidazole, polyimide, oxidized polyacrylonitrile, melamine, phenolic, polyolefins, polysulfonamide, liquid crystal polymer, polyvinylchloride, polytetrafluoroethylene, metal, glass, ceramic and/or other inorganic fibers. In addition, the flame and heat resistant yarns 10 also can be formed from blends or combinations of polyacrylate fibers and higher cost flame retardant fibers, such as para- or meta-aramids, polyimides, polybenzimidazole, polybenzoxazole, polysulfonamide and oxidized polyacrylonitrile fibers, to provide for a reduction in costs while still maintaining higher levels of flame and heat resistance protection.

The yarns 10 also can be plied, cabled, or twisted with various other types of yarns, including metal, glass, ceramic, and/or other types of inorganic yarns to form composite yarns incorporating various engineered properties.

The heat and flame resistant yarns 10 formed according to the principles of the present invention accordingly can be formed at significantly reduced costs versus conventional flame and heat resistant yarns, while still having a char strength sufficient to meet existing NFPA standards. The heat and flame resistant yarns 10 further can be formed into a variety of fabric and textile materials for use in a number of different applications. An example of such a fabric or textile material is illustrated in FIG. 2 (at 20) showing an ASTM D6413 testing of such a fabric. The heat and flame resistant yarns can be woven, knitted, or otherwise formed into various knit, woven and non-woven textile and/or fabric materials. Such flame and heat resistant fabrics generally will be formed with the polyacrylate fibers comprising a selected percentage of a total fiber weight of the flame and heat resistant yarn sufficient to provide a flame and heat resistant fabric formed from the flame and heat resistant yarn with a char length less than or equal to 4 inches when tested in accordance with ASTM D6413 Standard, and which meets or exceeds the vertical flammability requirements of any or all of NFPA 1971, NFPA 1975, NFPA 2112, NFPA 1951, NFPA 1977, and/or NFPA 70E Standards.

For example, such fabric materials could include protective fire and heat resistant clothing such as for fire-fighters, industrial workers and other personnel in which the danger of exposure to flames and high temperatures is an occupational hazard, as well as various other types of clothing such as shirts, pants, jackets or coats, coveralls, pajamas and other clothing in which it is desirable to protect the wearer against flammability. In addition, the heat and flame resistant yarns of the present invention further can be formed into sheeting or mat type materials for use in mattress fire blocking fabrics, bed sheets, blankets, tapestries, wall coverings, curtains, awnings, carpet, flooring materials, insulating materials, pillows, quilts, comforters, or luggage, and/or as a further alternative, can be used in fabric materials for upholstered furniture, thermal insulation, wall coverings, curtains, and/or seating for aircraft, trains, ships, buses, or automobiles. As a further alternative, the fabric materials further can be formed with additional yarns having other, varying constructions and/or from composite yarns formed by the flame and heat resistant yarns of the present invention being plied, cabled, twisted or otherwise combined with various other types of yarns. Such fabrics could include woven or knitted fabrics, for example, having the flame and heat resistant yarn of the present invention extending in one direction only or in an alternating weave or knitted pattern.

The following terms are defined in accordance with applicable ASTM and NFPA Standards:

The terms “flame retardant,” “flame resistant,” “fire resistant,” or “fire resistance,” as used herein, mean that the composition exhibits a Limiting Oxygen Index of at least 27%.

“Flame retardant,” “flame resistant,” “fire resistant,” or “fire resistance,” may also refer to the flame reference standard ASTM D6413 for textile compositions, flame spread test NF P 92-504, and similar standards for flame resistant fibers and textiles, as well as sufficient tensile and tear strength to resist tearing or rupture while remaining flexible after exposure to flames/fire. In addition, the terms “flame retardant” and “fire retardant” are distinguished from the terms “flame resistant” and “fire resistant” in that a flame or fire “retardant” fabric refers to a fabric which is more difficult to ignite and/or burns more slowly, while flame or fire “resistant” fabrics generally are not able to support a flame. The fabrics meeting the NFPA Standards are usually referred to as “flame resistant.” For example, NFPA 1971 defines Flame Resistance as “The property of a material whereby combustion is prevented, terminated, or inhibited following the application of a flaming or non-flaming source of ignition, with or without subsequent removal of the ignition source.”

After flame: “Persistent flaming of a material after ignition source has been removed.” [Source: ATSM D6413 Standard Test Method for Flame Resistance of Textiles (Vertical Method)].

Char length: “The distance from the fabric edge, which is directly exposed to flame to the furthest visible fabric damage, after a specified tearing force has been applied.” [Source: ATSM D6413 Standard Test Method for Flame Resistance of Textiles (Vertical Method)].

Drip: “A flow of liquid that lacks sufficient quantity or pressure to form a continuous stream.” [Source: National Fire Protection Association (NFPA) Standard 2112, Standard on Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire].

Melt: “The response to heat by a material resulting in evidence of flowing or dripping.” [Source: National Fire Protection Association (NFPA) Standard 2112, Standard on Flame-Resistant Garments for Protection of Industrial Personnel Against Flash Fire].

Self Extinguishing: Material will have no persistent flaming after the ignition source is removed OR flaming shall stop before the specimen is totally consumed when tested by ATSM D6413 Standard Test Method for Flame Resistance of Textiles (Vertical Method).

Char strength: The residual strength of a fiber or yarn after flame or thermal exposure when tested in accordance to ASTM D3822-07 Standard Test Method for Tensile Properties of Single Textile Fibers.

EXAMPLE

A fire retardant and heat resistant yarn formed according to the principles of the present invention was tested versus a conventional flame retardant yarn. The flame retardant and heat resistant yarn formed according to the principles of the present invention comprised a fiber blend including approximately 50 parts by weight (50%) of polyacrylate fibers and approximately 50 parts by weight (50%) of flame retardant viscose rayon fibers blended and spun into an approximately 265 denier staple fiber yarn. The flame retardant and heat resistant yarn was thereafter knitted into a fabric having a fabric weight of approximately 200 grams per square meter. For comparison, an approximately 265 denier yarn spun from 100 parts per weight (100%) of flame retardant viscose rayon fibers was knitted into a fabric having a fabric weight of approximately 200 grams per square meter.

Both fabric samples were tested for vertical flammability in accordance with ASTM test method D6413. An example of the test methodology used in accordance with ASTM D6413 is illustrated in FIG. 2. In the test, the fabric sample was exposed to a flame applied to the lower edge thereof for twelve seconds. After this time interval, the char length (i.e., the amount of charring found along the length of the fabric sample from the fabric edge exposed directly to the flame) was measured in accordance with method D6413. For the fabric sample formed from the flame retardant and heat resistant yarn formed according to the principles of the present invention, the measured char length was found to be less than four inches. By comparison, the fabric sample formed from the conventional yarn comprising 100% flame retardant viscose rayon fibers exhibited a char length that reached at least six inches after twelve seconds of exposure to an open flame.

In addition, fabrics incorporating the flame retardant and heat resistant yarn formed in accordance with Example 1 discussed above were dyed at 98° C. to a bright orange color without substantial variation in the dyeing of the fabric being observed.

Accordingly, when tested by method D6413, fabrics formed utilizing the flame retardant and heat resistant yarns formed according to the principles of the present invention have less than a four inch char length and was found to meet and/or to exceed the vertical flammability requirements of NFPA 1971, NFPA 1975, NFPA 2112, NFPA 1951, NFPA 1977, and NFPA 70E.

The embodiments of the invention and the various features thereof are explained in detail with reference to non-limiting embodiments and examples that are described and/or illustrated in the accompanying drawings. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and features of one embodiment may be employed with other embodiments as the skilled artisan would recognize, even if not explicitly stated herein. Descriptions of certain components and processing techniques may be omitted so as to not unnecessarily obscure the embodiments of the invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those of skill in the art to practice the embodiments of the invention. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the invention, which is defined solely by the appended claims and applicable law. Moreover, it is noted that like reference numerals represent similar parts throughout the several views of the drawings.

It further will be understood that the invention is not limited to the particular methodology, devices, apparatus, materials, applications, etc., described herein, as these may vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the invention. It must be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art in the field to which this invention is directed, and it will be understood that any methods and materials similar or equivalent to those described herein can be used in the practice or construction of the invention.

The foregoing description generally illustrates and describes various embodiments of the present invention. It will, however, be understood by those skilled in the art that various changes and modifications can be made to the above-discussed construction of the present invention without departing from the spirit and scope of the invention as disclosed herein, and that it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as being illustrative, and not to be taken in a limiting sense. Furthermore, the scope of the present disclosure shall be construed to cover various modifications, combinations, additions, alterations, etc., above and to the above-described embodiments, which shall be considered to be within the scope of the present invention. Accordingly, various features and characteristics of the present invention as discussed herein may be selectively interchanged and applied to other illustrated and non-illustrated embodiments of the invention, and numerous variations, modifications, and additions further can be made thereto without departing from the spirit and scope of the present invention as set forth in the appended claims. 

What is claimed:
 1. A flame and heat resistant yarn, comprising: a first series of fibers, comprising polyacrylate fiber; and a second series of fibers having a greater tensile strength than the polyacrylate fibers of the first series of fibers; wherein the first and second series of fibers are blended together to form the flame and heat resistant yarn, and wherein the polyacrylate fibers comprise a percentage of a total fiber weight of the flame and heat resistant yarn sufficient to provide a flame and heat resistant fabric formed from the flame and heat resistant yarn with a char length less than or equal to 4 inches when tested in accordance with ASTM D6413 Standard and with a fabric char length that which meets or exceeds any or all of NFPA 1971, NFPA 1975, NFPA 2112, NFPA 1951, NFPA 1977, and/or NFPA 70E Standards.
 2. The flame and heat resistant yarn of claim 1, wherein the second series of fibers comprises at least one fiber selected from the group comprising lyocell or viscose rayon, cotton, wool, polyesters, polyarnides, polyphenylene sulfide, polyetherimide, flame retardant lyocell, flame retardant viscose rayon, flame retardant wool, flame retardant cotton, flame retardant polyesters, flame retardant polyarnides, acrylic, modacrylic, polyolefins, metal, glass, ceramic and/or other inorganic fibers.
 3. The flame and heat resistant yarn of claim 2 further comprising an additional series of non-thermoplastic fibers selected from the group comprising: para-aramids, meta-aramids, phenolic, melamine, liquid crystal polymer, polyvinylchloride, polytetrafluoroethylene, oxidized polyacrylonitrile, polybenzimidazole, polybenzoxazole, and/or polysulfonamide.
 4. The flame and heat resistant yarn of claim 1, wherein the second series of fibers comprises at least one fiber selected from the group comprising para-aramids, meta-aramids, phenolic, melamine, liquid crystal polymer, polyvinylchloride, polytetrafluoroethylene, polybenzimidazole, polybenzoxazole, oxidized polyacrylonitrile, and/or polysulfonamide.
 5. The flame and heat resistant yarn of claim 1, wherein the polyacrylate fibers comprise about 2% to about 95% by weight of the yarn.
 6. The flame and heat resistant yarn of claim 1, wherein the polyacrylate fibers comprise about 5% to about 85% by weight of the yarn.
 7. The yarn of claim 1, wherein the polyacrylate fibers are dyed.
 8. The flame and heat resistant yarn of claim 1, wherein the flame and heat resistant yarn is plied, cabled, core spun or twisted with one or more other yarns.
 9. The flame and heat resistant yarn of claim 8, wherein the other yarns comprise metal, glass, and/or other inorganic yarns.
 10. A woven or knit fabric formed from the yarn of claim
 1. 11. The fabric of claim 10, wherein the polyacrylate fibers of the yarn are dyed.
 12. The fabric of claim 10, wherein the fabric comprises the yarn of claim 1 is woven or knitted with one or more other yarns having a different composition.
 13. A non-woven textile material formed from the yarn of claim
 1. 14. An article of manufacture formed from the yarn of claim 1, wherein the article of manufacture comprises shirts, pants, jackets, coveralls, hats, undergarments, and/or gloves.
 15. An article of manufacture formed from the yarn of claim 1, wherein the article of manufacture comprises a fire blocking fabric for mattresses and/or seating.
 16. The article of manufacture of claim 13, wherein the article meets or exceeds the performance of requirements promulgated in Code of Federal Regulations 16 CFR
 1633. 17. An article of manufacture formed from the yarn of claim 1, wherein the article of manufacture comprises bed sheets, blankets, upholstered furniture, tapestries, wall coverings, curtains, carpeting, flooring materials, insulating materials, pillows, quilts, comforters and/or luggage.
 18. An article of manufacture formed from the yarn of claim 1, wherein the article of manufacture comprises a thermal insulation, carpeting, wall coverings, curtains, or seating for aircraft, trains, ships, buses, and/or automobiles.
 19. A flame resistant fabric formed from the yarn of claim 1 which meets or exceeds the requirements for a SFI Foundation performance rating of 3.2A/1 to SFI 3.2A/40. 